The oil industry uses slotted metal pipe as a screening mechanism when drilling for heavy oil. Heavy oil is commonly found in oil bearing sand formations. Oil wells are drilled that have horizontal sections, which can be 1000 meters or more in length. These horizontal sections have a tendency to collapse and become filled with sand. In order to prevent this from occurring, slotted metal pipe is placed in the horizontal sections. The sand is supported by the metal pipe, while the heavy oil seeps through the slots into the pipe where it can be pumped to surface.
It is not unusual for the slots to have a width of between 25 and 15 thousandths of an inch. Even with slots of that width, some sand enters the pipe. In order to further restrict the entry of sand into the pipe, the industry is demanding slots of less than 15 thousandths of an inch. It has yet to be determined how small the slots can be without unduly restricting the rate of flow into the pipe. It has been speculated that between 5 and 7 thousandths of an inch will be optimum. Unfortunately, most slot cutting equipment is unable to cut slots with a width of less than 15 thousandths of an inch. German Offenlegungsschrift DE 32 13 46 A1 discloses slot cutting equipment capable of cutting multiple slots around a circumference of a pipe. The reference discloses a support for supporting a pipe in a horizontal orientation and a plurality of cutting heads positioned along the axial length of the pipe.